The odd character in the diner scene is actually one of the assailants later in the film called 'X', suggesting the four friends were being followed much earlier than they had ever realized.
The mesh shirt worn by the masked character 'Black' was worn by the actress who played lead character 'Vanessa', in the director Philip Carrer's first film, 'Desperate Souls'.
The scene at the beginning of the film where the character 'Laurie' wakes up bound and blindfolded, was shot on the day, and during an earthquake that was recorded at a 5.5 magnitude, which has been recorded to have been felt all the way from Ottawa to Toronto, and all the way to NY.